SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '328ef8323ee9321482ddbb6033b4df493aab1cb97feb112eec833bf3656a5464' 
  AND token = 'lLBx5Q4B48Rf1qzlxRdJ+ameM14wgyMGxyiJfKdjkZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}